Reason why: “When you turn from one task to another, you interrupt brain functions. Plus, multitasking adds stress and boosts toxic hormones such as cortisol, which clouds thinking and can destroy brain cells.”

If you love your job, you are among a small sliver of the U.S. workforce right now, a trend that should set off alarm bells in corner offices.

A Gallup poll released last week found a large chunk of U.S. workers are either actively disengaged at work or not inspired to work by their managers. The poll found only 30 percent, or roughly 30 million American workers, are engaged or inspired to work.

Worker disengagement can send ripples through the business world.

Engaged workers are much more productive at work, have fewer accidents and flat-out outperform disengaged workers. Gallup estimates that disengaged workers are costing businesses up to $550 billion a year.

"Engaged workers, though, have bought into what the organization is about and are trying to make a difference," said Jim Harter, Ph.D., Gallup's Chief Scientist of Employee Engagement and Wellbeing. "This is why they're usually the most productive workers."

According to Gallup, employee engagement is an important factor for any company, especially in a tough economy. These employees will produce more profit, be absent less and produce better work.

Those factors can inspire others and also trickle into the stock market, according to Gallup.

"Engaged employees are a lot closer to the best ideas," said Harter. "They're thinking about the whole company and how they fit into it, and their ideas lead to better decisions."

Gallup CEO Jim Clifton suggested one radical way to remake the U.S. workforce.

"Let's get rid of managers from hell, double the number of great managers and engaged employees, and have those managers lead based on what actually matters," he wrote in the foreword of the poll results.

That overhaul could make the workforce twice as effective, create more customers, shrink healthcare costs and help the nation's gross domestic product surge.